Boon for whale watchers, humpbacks have flooded Stellwagen Bank

Humpback whales are flooding into the coastal waters of Massachusetts this season with 20 to 30 whales spotted on every whale-watching excursion out of Boston, a hefty increase over the two or three that are usually spotted.

BOSTON — Humpback whales are flooding into the coastal waters of Massachusetts this season with 20 to 30 whales spotted on every whale-watching excursion out of Boston, a hefty increase over the two or three that are usually spotted.

Large numbers of an eel-like fish called the sand lance are turning the mouth of Massachusetts Bay into a "whale feeding ground," said Laura Howes of Boston Harbor Cruises.

"The past few weeks we have had exceptional whale activity," she said.

The whales have been drawn into Stellwagen Bank, an underwater plateau about 25 miles east of Boston, because of an increasing number of sand lances, Howes said.

Each of the school bus-sized humpback whales eat about a million of the 6-inch fish per day. An estimated 900 humpback whales live in the New England region.

"But what is driving this sand lance population is one of the big mysteries," said Dave Wiley, a scientist at the Stellwagen Bank National Marine Sanctuary who has been researching the sand lance since last year, when whale-watching cruises saw a particularly slow season.

Sand lances are attracted to Stellwagen Bank because of its sandy bottom, Wiley said, but he cannot explain why there were so few there last year.

"We just don't know too much about them, and we really need to," he said, adding that they are the top prey item in the southern Gulf of Maine.

The last extensive paper written on the species is from the 1970s. Wiley expects to finish up his research in a few years.

Despite the slow season, about 130,000 people went on whale-watches out of Boston last year.

And Boston Harbor Cruises expects that to go up with the recent abundance of whale sightings so early in the season.

However, although the numbers of whales seen on cruises might be uncommonly high, the number of whales in the region is not, said Charles "Stormy" Mayo, Provincetown Center for Coastal Studies right whale habitat studies director.

"The waters around Cape Cod and north of Cape Cod often have high concentrations of whales, and it's because of that high concentration that this region is known worldwide for its exceptional whale-watching," Mayo said. "The numbers that we are seeing now are exciting for whale-watchers but are not unusual in the waters around Cape Cod. We often see very high concentrations of whales responding to the influx of their food."